A broad bean plant covered in leaves and flowers but carrying few or no pods almost always comes down to pollination, not a fault with the plant. Broad beans need a fairly narrow temperature range to set viable pollen, and they rely on bees for cross-pollination on top of self-pollinating — so a cold snap, or simply a slow-warming season, can leave flowers producing nothing while the plant looks perfectly healthy.

Ranked, most likely first

  1. Cold weather at flowering. Broad beans need roughly 15-18°C to set viable pollen. A plant that flowers before the season has properly warmed keeps producing flowers without setting pods until conditions catch up — the flowering itself isn't the problem, the temperature at that exact moment is.
  2. Poor pollination weather. Even once it's warm enough, bees need to be active for good cross-pollination. Wet, windy or simply cold conditions keep bees away, and pods that do start in that window often turn black and drop rather than filling out.
  3. Nutrient shortfall or waterlogged soil. A plant short on nutrients, or sitting in soil too wet to take anything up, can flower heavily without following through into pods. This is a less common cause than temperature or pollination, worth checking only if the season has otherwise been settled.
  4. Heavy blackfly pressure. A plant carrying a dense, established aphid colony can also show reduced pod set — but this is a distinct, pest-driven cause you can rule in or out just by looking for aphids. See Why Are My Broad Beans Covered in Blackfly in NZ Cool/Mountain? if that's what you're actually seeing.

Why cold is the more likely culprit here

Our own broad beans calendar is identical across all three NZ zones — direct sow August to October, harvest December to February, Egmont-sourced — and both this zone and NZ Temperate share the same last spring frost month, November. So the frost-timing risk to open flowers is much the same either way. What genuinely differs is how quickly the growing season warms up overall. A cool/mountain garden runs cooler for longer through spring, and an August sowing here is more likely to flower before conditions reliably clear that 15-18°C pod-set threshold. If your beans are flowering steadily but not podding, cold is the first thing to suspect in this zone — ahead of bee activity or feeding, which matter more once temperatures are already in range.

What to do about it

  • Be patient through a cold or unsettled stretch. Flowers that don't set in a cold snap generally aren't wasted effort — the plant keeps flowering, and once the season warms and bees are active, later flushes set normally.
  • Plant bee-attracting flowers nearby so pollination is as efficient as possible once temperatures are no longer the limiting factor.
  • Pick off blackened, dropped pods so the plant puts its energy into new flowers rather than pods that have already failed.
  • Feed with a complete fertiliser if plants look pale or slow-growing alongside the lack of pods — Yates NZ specifically recommends a fish and seaweed-based feed for broad beans.
  • Check drainage if the ground has been consistently wet; broad beans need reasonable drainage to take up nutrients even while flowering well.
  • If you can see aphids clustering on the tips and flower stems in numbers, treat that as its own issue rather than assuming cold or pollination explains everything.

Cultivar notes

None of our sourced cultivars for this zone — Coles Prolific, Red Seeded, Scottish, Superaguadulce, and Suttons Dwarf — carry a specific claim about cold tolerance at flowering or pod-set performance; their notes cover sowing method and timing rather than this problem. So there's no variety swap that fixes cold-driven pod failure directly — timing your sowing so flowering lands later in the warm-up, where practical, matters more than cultivar choice here.

Next season

If this happens most years, consider whether an August sowing is pushing flowering into the coldest stretch of your particular garden's warm-up — a slightly later sowing within the August-October window may let flowering land closer to the point where pollen reliably sets, though that's a timing adjustment worth testing locally rather than a guaranteed fix.

More on this zone: see the full NZ Cool/Mountain Planting Calendar →.